Re: [Phys-L] music scales

[Paul Nord <Paul.Nord@valpo.edu>]

Also notice that what you've got there is the standard "physics" set of
tuning forks.  The 256 Hz is close to the common tuning for a C.  However,
in the usual equal tempered scale the frequency is closer to 262 Hz.  A 256
Hz tuning fork seems to have been developed for physics classrooms.  It's
easy to do the math to show that 512 Hz and 1024 Hz are simple octaves.

Each half step on the musical keyboard is separated by a ratio of 2^(1/2).
Going down 9 half steps from A 440 Hz we get:
2^(-9/12) * 440 = 261.63 Hz

Paul

On Sat, Feb 15, 2025 at 9:17 PM Anthony Lapinski via Phys-l <
phys-l@mail.phys-l.org> wrote:

> I'm teaching a sound unit (in my high school class) in a few months. I was
> reading/revising some of my class notes and wanted to add a small section
> about tuning forks when I introduce waves and frequency.
>
> I have a standard set of tuning forks (C D E F G A B C) with these
> frequencies (Hz):
>
> 256, 288, 320, 341.3, 384, 426.6, 480, 512
>
> I often wondered why two of them (F, A) were decimals...
> They sound like a normal scale.
> So (512 - 256)/8 = 32 Hz
>
> The first three (C, D, E notes) differ by 32, as do the last two (B, C
> notes); the others don't.
>
> I then searched the history of tuning forks and came across the equal
> temperament scale (same frequency ratio of adjacent notes):
>
> 261.3, 293.66, 329.63, 349.23, 392, 440, 493.88, 523.25
>
> Pianos and guitars are tuned to this scale. Any other instruments?
>
> I'm NOT a musician. Does anyone know when and why these scales were
> developed? And why aren't standard tuning forks equal temperament to match
> what some instruments produce? Any information, web references, or
> textbooks will be much appreciated. Thanks!
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